Acid milk beverages of a type containing living microbes, such as a fermented milk, a lactic acid bacteria beverage and a yogurt have been widely taken as a healthy drink which has physiological activities, such as an effect of calming intestinal disorders and immunopotentiative action.
In addition, various types of acid milk beverages have been proposed for responding to diversifying customer preferences. Among them, acid milk beverages of a type which contains a low solids-not-fat have also been developed.
However, dispersibility of milk protein usually becomes unstable under an acid condition, and therefore, in an acid milk beverage, there is a problem of precipitation, aggregation, separation of whey, and the like being easily produced. When the solids-not-fat content is low, distances between the milk proteins are long and therefore the repulsive forces between the electric charges are weak and precipitation or aggregation is easily produced.
The above-mentioned precipitation, aggregation or whey separation not only deteriorate the appearance significantly but also affect the taste upon drinking and further deteriorate the refreshing feel. Accordingly, methods of using various thickening stabilizers have been proposed for improving the problem. Specifically, a method of using carboxymethyl cellulose (CMC) has been proposed (Patent Documents 1 and 2).
However, when CMC was used as described above, a product having a refreshing texture could not be obtained. In particular, such a product had a property of becoming gel in a low pH region, and it was more difficult to obtain a product having a refreshing texture.